The present invention relates to a method of recording data on a recording medium, wherein the data include MPEG video data and first sub-title data. Furthermore, the present invention relates to a device for recording these data on a recording medium.
According to the generally available DVD standard the MPEG format provides up to 32 sub-picture streams. Usually, such sub-picture streams are used to record various sub-titles, e.g. in different languages, on a DVD disc. Thus, when replaying a DVD disc the user has the possibility to choose a specific sub-title which is displayed on the video screen together with video data.
The recording of a plurality of sub-titles by sub-picture streams on a DVD disc requires a complex recording technique. Therefore, video recorders have been developed, the recording technique of which is less complex and less expensive but which can only record one sub-picture stream. A corresponding DVD-VR standard has been defined which describes the specific video recording on DVD discs. The user replaying the video signals stored on the DVD-VR disc has the possibility to switch on and off the sub-title of the one sub-picture stream. However, he does not have the possibility to choose another sub-title, as he can choose when replaying a DVD disc.
Moreover, according to the state of art, it is possible to xe2x80x9cburnxe2x80x9d a sub-title into a video stream. However, such a sub-title is always visible when playing back the corresponding video part.
In view of the above-described disadvantages it is an object of the present invention to provide a method and device for making available more than one sub-title to the user when replaying a DVD-VR disc.
According to the present invention this object is solved by a method of recording data on a recording medium, wherein the data include MPEG video data and first sub-title data, with a step of storing at least second sub-title data as character based information within the MPEG video data.
The advantage of storing additional sub-title data in the MPEG video stream is, that additional sub-title information is available to the user if he has a corresponding decoder which is able to extract these additional sub-title data from the MPEG video stream. The features of individually using the sub-title data of the sub-picture stream are not affected by storing the additional sub-title data within the MPEG video stream.
According to an enhanced DVD-VR standard it may be possible to record one or more additional sub-picture streams on a DVD-VR disc. Thus, more than one sub-title stream may be recorded as sub-picture stream on the disc. Alternatively, more than one sub-title stream may be recorded within the MPEG video stream. Closed Caption, for example, provides such feature of storing more than one sub-title.
Preferably, the sub-title data obtained from a sub-picture stream are stored as Teletext, Videotext or Closed Caption. The specific advantage of using the Teletext, Videotext or Closed Caption format is that most television sets currently available on the market are already provided with corresponding decoders. Therefore, a user having a DVD player and a TV-set with a Teletext decoder has the possibility to conventionally activate a first sub-title stream stored in a sub-picture stream on the DVD-VR disc and, furthermore, he can activate the sub-title stream stored within the video stream as usual Teletext by switching on the Teletext decoder.
In a preferred embodiment the character based sub-title information is labelled by a flag inside the sub-title data, so that corresponding data can be automatically identified as sub-title information.
Furthermore, as already described above the video and sub-title data may be recorded on the DVD disc together with further data as digital information.
MPEG video streams provide space for storing user data in picture layers or GOP (group of pictures) layers. This space is preferably used to transmit or record Teletext, Videotext or Closed Caption data.
The method of recording sub-title data may be improved by analysing the at least one incoming sub-picture stream. Such analysis is necessary for improving a transformation from the sub-picture format into the Teletext, Videotext or Closed Caption format.
As already described above, DVD-VR used according to the present invention provides the possibility of recording at least two sub-title streams. Both sub-title streams may be output from a DVD disc. The first sub-title stream may be stored conventionally within a sub-picture stream. The second sub-title stream may be stored for example as Teletext. However, one of the sub-title streams or all of them may also be individually input by the user, for example with a keyboard. Thus, the user can input individual data streams to be stored on the DVD-VR disc either as Teletext or as sub-picture data. E.g. the user can input sub-titles personally translated to another language, generate a sub-title stream for another target group or record information, which is automatically generated and related to the content of the video stream, like the current date and time.
Moreover, according to the present invention the above described methods may be implemented on a device for recording data on a recording medium, wherein the data include MPEG video data and first sub-title data, with recording means for recording at least second sub-title data as character based information within the MPEG video data. Additional transcoding means may be provided for transcoding sub-title data from the MPEG sub-picture format to Teletext, Videotext or Closed Caption format.
The inventive method is usually formulated as computer program so that it may run on a plurality of hardware devices. For installation the computer program usually will be stored on recording media like data discs.